Technically, nothing notes this is steel, but I digress.
We've seen Sanji strike at people using Tekkai. These same people who were able to block attacks from Zoro. Furthermore, Kaku could use Rankyaku and then guard it with Tekkai, and this same move Zoro had to make effort just to block. Suggesting Tekkai is basically of steel hardness or better. Sanji bested the best Tekkai user in CP-9 (Jyabura). Furthermore, I believe Blueno notes that tekkai transforms their bodies to be hard like steel.
It is likely he'd be able to harm Daz.
